In U.S. Pat. No. 5,419,318, a breathing mask is disclosed which features a soft, flexible face contacting member and outer filtration shell member fastened thereto to form a mask. The face contacting member is three-dimensionally formed in an arcuate shape that provides a cup in which the chin of the mask wearer rests in order to prevent the mask from slipping under the chin of the wearer. The outer shell member is either an air permeable filtration material or may be a rigid air impervious material through which air filtration element(s) are mounted to filter breathed air. U.S. Pat. No. 5,419,318 enables one to manufacture face masks that fit and provide an effective seal for more than one wearer's size by combining single size filtration shells with more than one size soft, flexible face contacting members, formed in more than one size arcuate shapes, featuring more than one size chin cups, having more than one size inner breathing openings and fastened to the single size filtration shells at the same outer periphery.
As shown in FIG. 1, face mask 100, placed on small size wearer's face 101a (shown in solid line), combines filtration shell 102 with small size face contacting member 103a, formed in small size arcuate shape 104a and having small size chin cup 105a and small size inner breathing opening 106a. Small size face contacting member 103a and filtration shell 102 are fastened to each other at outer periphery 107. Also, as shown in FIG. 1, face mask 100, placed on large size wearer's face 101b (shown in dashed line) combines same size filtration shell 102 with large size face contacting member 103b, formed in large size arcuate shape 104-b and having large size chin cup 105-b and large size inner breathing opening 106b. Large size face contacting member 103b and same size filtration shell 102 are fastened to each other at same outer periphery 107.
Another known mask, manufactured by Minnesota Mining and Manufacturing Company of St. Paul, Minn. (Style No. 9970), features, as shown in FIGS. 2 and 2B, a single size filtration shell 202 attached to soft flexible planar face contacting member 203. In various sizes of face mask 200, planar face contacting member 203 appears to have approximately the same size inner breathing opening 206 and appears to be fastened to filtration shell 202 at approximately the same outer periphery 207. It is important and relevant to the present invention to also point out that inner breathing opening 206 is of an elliptical shape and is symmetric around axes X-X and Y-Y. As such, in order to conform face contacting member 203 to the shape of a wearer's face, a deformable strip (nose clip) 208 is attached onto filtration shell 202. Deformable strip 208 is shaped by the wearer to fit around his/her nose bridge in order to provide a seal. Mask 200 also features exhalation valve 209 and head band length adjustment brackets 210.
A third known mask, manufactured by Racal Health and Safety, Inc., Frederick of Maryland (Style No. Delta 3), features, as shown in FIGS. 3 and 3A, a filtration shell 302 attached to soft, flexible face contacting member 303. In various sizes of mask 300, various sizes of filtration shell 302 are attached to various sizes of soft, flexible face contacting member 303, having more than one size inner breathing opening 306, at distinctly different size outer peripheries 307. Again, it is important and relevant to the present invention to point out that inner breathing opening 306 is of a race track shape and is symmetric around axes X-X and Y-Y. As such and likewise, in order to conform face contacting member 303 to shape of wearer's face, a deformable nose clip 308 is attached to filtration shell 302 and shaped as described above. Mask 300 also features an exhalation valve 309.
Examination of the latter masks reveals a number of limitations, disadvantages and/or design inconsistencies, including: (1) producing a specific shape/size arcuate shape face contacting member for each wearer's size is costly; (2) producing a specific size filtration shell and a specific size face contacting member for each wearer's size is not only costly but also results in a higher breathing resistance and lower filtration efficiency in small size masks due to the smaller filtration area in small size masks; (3) attaching a single size filtration shell to face contacting members, having approximately the same size inner breathing opening at approximately the same outer periphery, yields masks of nominally different sizes but actually poor fit characteristics. Such poor fit was the subject of a report published by Dr. Helson Leidel, formerly associated with the National Institute for Occupational Safety and Health (NIOSH) in 1994; and (4) using an inner breathing opening with symmetry about axis X-X (as shown in FIGS. 2 and 3) is inconsistent with how the facial nose area is inherently smaller and of narrower width than the mouth and chin area.
The present invention overcomes the limitations, disadvantages and design inconsistencies of these known masks by providing different size face masks in which a single size filtration shell is attached to a single size face contacting member at the same periphery, wherein the single size face contacting member has one, of more than one size, inner breathing opening with a narrower cut profile in the nose area than in the mouth and chin area. Such different size face masks would fit and provide an effective seal for more than one size of wearer. A face mask that provides the above features would not only eliminate all of the above-mentioned limitations, disadvantages and design inconsistencies, but also have significant cost, manufacturing, and inventory control advantages.
The present invention also provides a face mask which, in addition to eliminating slippage relative to the wearer's face by deforming the flexible face liner to form a chin cup and providing an effective seal to the wearer's face, has no contact between the wearer's face and the filtration shell thereby ensuring a maximum area for flow of filtered air and, therefore, a minimum breathing resistance regardless of the wearer's face size.